1. Field of the Invention
The present invention relates to an apparatus for attaching a fastener such as a snap closure, a button, a tack, a rivet, or the like composed of male and female fastener members to a web-like material such as a fabric.
2. Description of the Prior Art
One known apparatus for attaching fasteners of the type described to fabric materials is illustrated in Japanese Laid-Open Patent Publication No. 56-85407. In the disclosed apparatus, a pair of clamps defining a pocket for holding an upper fastener member is mounted on a lower end of a punch holder case, and the clamps are urged toward each other by leaf springs. However, unless the leaf springs apply equal resilient forces to the clamps, the pocket tends to be displaced out of a centered position. When an upper fastener member is to be supplied into the pocket, therefore, it cannot be reliably and smoothly accommodated in the pocket. Furthermore, the upper fastener member in the pocket may not be properly combined with a lower fastener member on a die due to misalignment. According to another known arrangement, a pocket is defined by a pair of clamp members urged by a compression coil spring acting therebetween for gripping a fastener member in the pocket. However, the compression coil spring directly engaging the clamp members may often fail to center the fastener member as desired.
The prior fastener attaching apparatus of the type referred to above includes a punch movable by a drive mechanism such as an air cylinder toward a die for pressing fastener members together. There are known certain safety mechanisms for preventing fingers or tools from being sandwiched between the punch and the die, the examples including a safety cover between the punch and the die and a special safety device associated with the apparatus. However, such prior safety measures have resulted in an increased size of the apparatus, a small field of view in which the operator can visually supervise the operation of the apparatus, and difficulty in removing fastener members from between the punch and the die.
The apparatus shown in Japanese Laid-Open Patent Publication No. 56-85407 includes a parts feeder composed of a conical rotary drum having equally spaced grooves in which base portions of fastener members are fitted. The fastener members can be supplied to a chute by rotating the rotary drum. When dust or machined chips happen to enter grooves in the rotary drum, the fastener members fail to be supplied to the chute or are liable to hit a hopper frame for preventing rotation of the drum. The jamming fastener member has to be removed out of the groove by striking or vibrating the drum. Thus, the apparatus is required to be stopped for removal of such a jam, with the result that the efficiency of the apparatus is lowered. The jam-removing process is also quite tedious and time-consuming.
Another problem is that the rotary drum makes the overall apparatus large in size. It is difficult to position the drum with respect to the chute. When it is found that the drum and chute are improperly positioned with respect to each other, then the chute has to be detached and then positioned again relative to the drum.